Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 43
e ofthe circle. Also, a line drawn through the centre of the cir-cle and perpendicular to the chord,bisects it. THEOREM III. If more than two equal lines can be drawn from any point witfuna circle to the circumference, that point will be the centre. Let D be any point within the circleABC. Then, if… … BOOK II 43 Of the Circle Then, since the two triangles DAE and DEB have the sideAE equal to EB, AD equal to DB, and DE common, theywill be equal in all respects; and consequently, the angleDEA is equal to the angle DEB (Bk. I. Th. viii); andtherefore, DE is perpendicular to AB (Bk. I. De[. 20)…
Geometry · Plane trigonometry
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
